Various embodiments are already known of locking insert devices for tire chambers, i.e. devices which when placed inside tubeless tires mounted on wheel rims prevent the beads of the tires from coming off their seats on the wheel rim, in particular when said rim is of the well or drop center type thus enabling the wheels fitted therewith to conserve their vehicle-driving ability even with punctured tires. Such devices are described, for instance in British Patent 1 348 892 or French Patents 2 311 667 and 2 271 945. Those known embodiments, which are generally intended for military vehicles or for very special civilian vehicles, are too expensive to be implemented on ordinary road transport vehicles such as trucks, buses, coaches, etc.